Your development web server is behind a firewall, ,but you have acceess to an outward-bound proxy and you want to query a whois server somewhere on the internet?
I have never done that - but if I were to try it in perl, I would use LWP to connect to the proxy and send an http query to the whois server.]
I don't know if php has a similar module, but it would be worth trying (Maybe try curl). Lookup curl support on php.net (I know that oasis adserver which is driven by php uses curl).
hmmm....
good luck